Quiescin Sulfhydryl Oxidase 1 (QSOX1) Secreted by Lung Cancer Cells Promotes Cancer Metastasis.

As lung cancer shows the highest mortality in cancer-related death, serum biomarkers are demanded for lung cancer diagnosis and its treatment. To discover lung cancer protein biomarkers, secreted proteins from primary cultured lung cancer and adjacent normal tissues from patients were subjected to LC/MS⁻MS proteomic analysis. Quiescin sulfhydryl oxidase (QSOX1) was selected as a biomarker candidate from the enriched proteins in the secretion of lung cancer cells. QSOX1 levels were higher in 82% (51 of 62 tissues) of lung cancer tissues compared to adjacent normal tissues. Importantly, QSOX1 serum levels were significantly higher in cancer patients (p < 0.05, Area Under curve (AUC) = 0.89) when measured by multiple reaction monitoring (MRM). Higher levels of QSOX1 were also uniquely detected in lung cancer tissues, among several other solid cancers, by immunohistochemistry. QSOX1-knock-downed Lewis lung cancer (LLC) cells were less viable from oxidative stress and reduced migration and invasion. In addition, LLC mouse models with QSOX1 knock-down also proved that QSOX1 functions in promoting cancer metastasis. In conclusion, QSOX1 might be a lung cancer tissue-derived biomarker and be involved in the promotion of lung cancers, and thus can be a therapeutic target for lung cancers.

Stanniocalcin-2 (STC2): A potential lung cancer biomarker promotes lung cancer metastasis and progression.

The homodimeric glycoprotein, stanniocalcin 2 (STC2) is previously known to be involved in the regulation of calcium and phosphate transport in the kidney and also reported to play multiple roles in several cancers. However, its function and clinical significance in lung cancer have never been reported and still remain uncertain. Here, we investigated the possibility of STC2 as a lung cancer biomarker and identified its potential role in lung cancer cell growth, metastasis and progression. Proteomic analysis of secretome of primary cultured lung cancer cells revealed higher expression of STC2 in cancers compared to that of adjacent normal cells. RT-PCR and Western blot analyses showed higher mRNA and protein expressions of STC2 in lung cancer tissues compared to the adjacent normal tissues. Knockdown of STC2 in H460 lung cancer cells slowed down cell growth progression and colony formation. Further analysis revealed suppression of migration, invasion and delayed G0/G1 cell cycle progression in the STC2 knockdown cells. STC2 knockdown also attenuated the H202-induced oxidative stress on H460 cell viability with a subsequent increase in intracellular ROS levels, which suggest a protective role of STC2 in redox regulatory system of lung cancer. These findings suggest that STC2 can be a potential lung cancer biomarker and plays a positive role in lung cancer metastasis and progression. This article is part of a Special Issue entitled: Medical Proteomics.

Integrated glycoproteomics demonstrates fucosylated serum paraoxonase 1 alterations in small cell lung cancer.

Small cell lung cancer (SCLC) is an aggressive type of lung cancer, and the detection of SCLCs at an early stage is necessary for successful therapy and for improving cancer survival rates. Fucosylation is one of the most common glycosylation-based modifications. Increased levels of fucosylation have been reported in a number of pathological conditions, including cancers. In this study, we aimed to identify and validate the aberrant and selective fucosylated glycoproteins in the sera of patients with SCLC. Fucosylated glycoproteins were enriched by the Aleuria aurantia lectin column after serum albumin and IgG depletion. In a narrowed down and comparative data analysis of both label-free proteomics and isobaric peptide-tagging chemistry iTRAQ approaches, the fucosylated glycoproteins were identified as up- or down-regulated in the sera of limited disease and extensive disease stage patients with SCLC. Verification was performed by multiple reaction monitoring-mass spectrometry to select reliable markers. Four fucosylated proteins, APCS, C9, SERPINA4, and PON1, were selected and subsequently validated by hybrid A. aurantia lectin ELISA (HLE) and Western blotting. Compared with Western blotting, the HLE analysis of these four proteins produced more optimal diagnostic values for SCLC. The PON1 protein levels were significantly reduced in the sera of patients with SCLC, whereas the fucosylation levels of PON1 were significantly increased. Fucosylated PON1 exhibited an area under curve of 0.91 for the extensive disease stage by HLE, whereas the PON1 protein levels produced an area under curve of 0.82 by Western blot. The glycan structural analysis of PON1 by MS/MS identified a biantennary fucosylated glycan modification consisting of a core + 2HexNAc + 1Fuc at increased levels in the sera of patients with SCLC. In addition, the PON1 levels were decreased in the sera of the Lewis lung carcinoma lung cancer mouse model that we examined. Our data suggest that fucosylated protein biomarkers, such as PON1, and their fucosylation levels and patterns can serve as diagnostic and prognostic serological markers for SCLC.

Novel functional Renilla luciferase mutant provides long-term serum stability and high luminescence activity.

Fluorescent and luminescent chemical probes are essential in recent medical diagnostics. However, the use of these probes in vivo has raised concerns due to their low sensitivity, background signal interference, and non-biocompatibility. Therefore, biological chromophores have received much attention as new alternatives. In particular, luciferase, a class of oxidative enzyme with bioluminescence, has emerged as a promising fluorophore due to its improved biocompatibility. However, the enzyme usually possesses weaker luminescence and stability relative to its chemically-based competitors. Here, we report a novel functional mutant luciferase with both enhanced luminescence and long-term serum stability. For the preparation of the modified Renilla luciferase, a new bacterial subcloning design was established. The luciferase coding DNA sequence was redesigned so that mutant luciferase could be easily expressed in an Escherichia coli system. The mutant Renilla luciferase, which we called "m-Rluc," demonstrated characteristic enzymatic functions and showed a 5.6-fold increase in luminescence activity. In addition, the enzyme's physiological stability remained >80% for more than 5days, in contrast to conventional luciferase, termed "hrluc," which disappeared within a few hours. We suggest that this novel biological luciferase probe may be a great tool for both in vitro and in vivo medical diagnostics.

Multi-targeted therapy resistance via drug-induced secretome fucosylation.

Cancer secretome is a reservoir for aberrant glycosylation. How therapies alter this post- translational cancer hallmark and the consequences thereof remain elusive. Here, we show that an elevated secretome fucosylation is a pan-cancer signature of both response and resistance to multiple targeted therapies. Large-scale pharmacogenomics revealed that fucosylation genes display widespread association with resistance to these therapies. In cancer cell cultures, xenograft mouse models, and patients, targeted kinase inhibitors distinctively induced core fucosylation of secreted proteins less than 60 kDa. Label-free proteomics of N-glycoproteomes identified fucosylation of the antioxidant PON1 as a critical component of the therapy-induced secretome (TIS). N-glycosylation of TIS and target core fucosylation of PON1 are mediated by the fucose salvage-FUT8-SLC35C1 axis with PON3 directly modulating GDP-Fuc transfer on PON1 scaffolds. Core fucosylation in the Golgi impacts PON1 stability and folding prior to secretion, promoting a more degradation-resistant PON1. Global and PON1-specific secretome de-N-glycosylation both limited the expansion of resistant clones in a tumor regression model. We defined the resistance-associated transcription factors (TFs) and genes modulated by the N-glycosylated TIS via a focused and transcriptome-wide analyses. These genes characterize the oxidative stress, inflammatory niche, and unfolded protein response as important factors for this modulation. Our findings demonstrate that core fucosylation is a common modification indirectly induced by targeted therapies that paradoxically promotes resistance.

Identification and validation of SAA as a potential lung cancer biomarker and its involvement in metastatic pathogenesis of lung cancer.

Lung cancer is recently regarded as an overhealed inflammatory disease. Serum amyloid A (SAA) is known as an acute phase protein, but it is likely involved in the cancer pathogenesis. We identified both SAA1 and SAA2 in the pooled sera of lung cancer patients but not in the healthy control, by LC-MS/MS analysis. We found that about 14-fold higher levels of SAA in lung cancer patients' sera and plasma compared to healthy controls by ELISA using total 350 samples (13.89 ± 37.18 vs 190.49 ± 234.70 ug/mL). The SAA levels were also significantly higher than in other pulmonary disease or other cancers. An immunohistochemical study using tissue microarray showed that, unlike other cancer tissues, lung cancer tissues highly express SAA. Further in vitro experiments showed that SAA is induced from lung cancer cells by the interaction with THP-1 monocytes and this, in return, induces MMP-9 from THP-1. In in vivo animal models, overexpressed SAA promoted Lewis lung carcinoma (LLC) cells to metastasize and colonize in the lung. Our data suggest that a higher concentration of SAA can serve as an indicator of lung adenocarcinoma and represents a therapeutic target for the inhibition of lung cancer metastasis.

Proteomic approaches in lung cancer biomarker development.

Biomarker discovery is one of the newly emerging innovations in the diagnosis and treatment of cancer and many other diseases. Many research groups and large pharmaceutical companies are actively engaged in searching for novel biomarkers for malignant diseases, which will make molecular analysis and monitoring of disease possible. Many technologies, including genomics, proteomics and metabolomics, are used to identify biomarkers. Among the many types of cancers and diseases, lung cancer--owing to the difficulty in diagnosing the disease at an early stage--urgently needs development of novel biomarkers as tools for early diagnosis and detection, as well as disease monitoring. Several DNA and protein biomarkers have been identified, but most previously discovered biomarkers are correlated with the general process of carcinogenesis and immune responses. Therefore, many of these biomarkers are found in other types of cancers, and thus are not specific to lung cancer. Therefore, novel lung cancer biomarker discovery is still needed, and among the many possible types of samples, blood is thought to be ideal for this discovery as it can be collected easily in a minimally invasive manner. Therefore, many studies are now being conducted to find lung cancer biomarkers in the blood. With advances in methods and technology, together with the considerable efforts to find early and novel diagnostic lung cancer biomarkers, many candidates will be discovered; leading to early diagnosis, detection, monitoring and efficient treatment of lung cancers.

Upregulation of Complement Factor H by SOCS-1/3⁻STAT4 in Lung Cancer.

Complement factor H (CFH) is a fluid phase regulator of complement proteins and functions to prevent complement attack and immune surveillance. CFH is known to inactivate therapeutic antibody-dependent complement-mediated cellular cytotoxicity. We found that CFH was highly expressed in human lung cancer cells and tissues. To investigate mechanisms of CFH upregulation, we searched for a CFH transcription factor and its regulatory factors. First, signal transducer and activator of transcription 4 (STAT4) expression patterns coincided with CFH expression patterns in lung cancer tissues. Knockdown of STAT4 led to decreased CFH secretion from lung cancer cells. STAT4 bound directly to the CFH promoter, as demonstrated by luciferase reporter assay, electrophoretic mobility shift assay (EMSA), and chromatin immunoprecipitation (ChIP) assay, suggesting that STAT4 is a transcription factor for CFH. In addition, a low level of suppressors of cytokine signaling (SOCS)-1/3, a Janus kinase (JAK) inhibitor, was observed in lung cancer cells and its transfection decreased CFH protein levels and promoter activity. Unexpectedly, the low level of SOCS-1/3 was not due to epigenetic silencing. Instead, differential methylation was found on the regulatory region of STAT4 between normal and lung cancer cells. In conclusion, our results demonstrated that CFH is upregulated by constitutive activation of STAT4, which is accounted for by SOCS silencing in lung cancer cells.

Deficiency of DGCR8 increases bone formation through downregulation of miR-22 expression.

MicroRNAs (miRNA) significantly contribute to bone formation by post-transcriptional regulation of gene expression. Mature miRNAs are generated following sequential cleavage by DROSHA/DGCR8 and DICER. However, recent studies have identified that some miRNAs require only one of these enzymes. Most studies seeking to clarify the role of miRNA during bone formation have been performed using DICER deletion strategies, but little is known regarding the role of DGCR8. To study the function of DGCR8 in osteogenesis, we generated mice in which Dgcr8 is conditionally deleted in osteoprogenitor cells by Col1a1-Cre. Dgcr8-cKO mice showed increased bone volume (BV/TV), trabecular number (Tb/N), and trabecular thickness (Tb.Th), but decreased trabecular separation (Tb.Sp) in the femur. Von Kossa, tartrate-resistant acid phosphatase staining, and calcein double labeling identified that osteoblast activity is increased in Dgcr8-cKO mice. In an effort to elucidate a detailed cellular mechanism, we found that miR-22 was downregulated in Dgcr8-cKO mice, leading to upregulation of the osteocalcin transcript, a key marker of osteoblasts. Interestingly, the mRNA expression level of Dgcr8 was decreased during osteoblast differentiation. Taken together, these results strongly indicate that DGCR8-dependent generation of miR-22 is essential for bone formation and that miR-22 could be a therapeutic target for individuals with bone disease.

Paraoxonase-1 (PON1) induces metastatic potential and apoptosis escape via its antioxidative function in lung cancer cells.

Paraoxonase-1 (PON1) gene polymorphisms have been closely associated with the development of advanced cancers while PON1 secretion to the serum is linked with inhibition of oxidized high-density lipoprotein by its antioxidative function. Our group previously demonstrated that post-translational modification of serum PON1 in form of fucosylated PON1 is a potential biomarker of small cell lung cancer. Here, we interrogated the role of PON1 in the pathobiology of lung cancer (LC) by addressing cell-autonomous mechanisms using gain-of-function and loss-of-function approaches and protein expression profiling of tissue samples in our clinical biobank. PON1 expression in LC patient tissues varied between overexpression in squamous cell carcinoma and minimal loss in adenocarcinoma sub-types. Simultaneous overexpression of PON1 both at the gene and protein stability levels induced pro-oncogenic characteristics in LC cells and xenografts. PON1 overexpression supported metastatic progression of LC by decreasing G1/S ratio and LC cell senescence involving p21Waf1/Cip1. PON1 suppressed drug- and ligand-induced cell death and protected LC cells from genotoxic damages with maintained ATP levels, requiring p53-directed signals. PON1 promoted ROS deregulation protecting the mitochondria from dysregulation. PON1 knockdown resulted in the blockage of its antioxidant function in LC cells through Akt signaling with reduced invasive signature as a consequence of scant expression. Targeted glycolysis stimulated PON1 antioxidant activity regulating phosphorylation of AMPK-α. The functional data imply that exploitation of the antioxidative function of PON1 is consequential in driving LC pathogenesis at the cell-autonomous mechanistic level with consequences on tumor growth.

Radical scavenging and anti-inflammatory activity of extracts from Opuntia humifusa Raf.

Opuntia humifusa Raf. (O. humifusa Raf.) is a member of the Cactaceae family. To determine the antioxidative and anti-inflammatory effects of this herb, various solvent fractions (methanol, hexane, chloroform, ethyl acetate, butanol, and water) prepared from the leaves of cacti were tested using DPPH (2,2-diphenyl-l-picrylhydrazyl radical) and xanthine oxidase assays, and nitric oxide (NO)-producing macrophage cells. We found that O. humifusa Raf. displayed potent antioxidative and anti-inflammatory activity. Thus, all solvent fractions, except for the water layer, showed potent scavenging effects. The scavenging effect of the ethyl acetate fraction was higher than that of the other fractions, with IC50 values of 3.6 and 48.2 microg mL(-1). According to activity-guided fractionation, one of the active radical scavenging principles in the ethyl acetate fraction was found to be quercetin. In contrast, only two fractions (chloroform and ethyl acetate) significantly suppressed nitric oxide production from the lipopolysaccharide (LPS)-activated RAW264.7 cells. In addition, chloroform and ethyl acetate fractions significantly blocked the expression of inducible nitric oxide synthetase (iNOS) and interleukin-6 (IL-6) from the RAW264.7 cells stimulated by LPS. Moreover, ethyl acetate fractions significantly blocked the expression of IL-1beta from the RAW264.7 cells stimulated by LPS. Therefore, the results suggested that O. humifusa Raf. may modulate radical-induced toxicity via both direct scavenging activity and the inhibition of reactive species generation, and the modulation of the expression of inflammatory cytokines. Finally, O. humifusa Raf. may be useful as a functional food or drug against reactive species-mediated disease.

Meta-markers for the differential diagnosis of lung cancer and lung disease.

UNLABELLED: Misdiagnosis of lung cancer remains a serious problem due to the difficulty of distinguishing lung cancer from other respiratory lung diseases. As a result, the development of serum-based differential diagnostic biomarkers is in high demand. In this study, 198 clinical serum samples from non-cancer lung disease and lung cancer patients were analyzed using nLC-MRM-MS for the levels of seven lung cancer biomarker candidates. When the candidates were assessed individually, only SERPINEA4 showed statistically significant changes in the serum levels. The MRM results and clinical information were analyzed using a logistic regression analysis to select model for the best 'meta-marker', or combination of biomarkers for differential diagnosis. Also, under consideration of statistical interaction, variables having low significance as a single factor but statistically influencing on meta-marker model were selected. Using this probabilistic classification, the best meta-marker was determined to be made up of two proteins SERPINA4 and PON1 with age factor. This meta-marker showed an enhanced differential diagnostic capability (AUC=0.915) for distinguishing the two patient groups. Our results suggest that a statistical model can determine optimal meta-markers, which may have better specificity and sensitivity than a single biomarker and thus improve the differential diagnosis of lung cancer and lung disease patients. BIOLOGICAL SIGNIFICANCE: Diagnosing lung cancer commonly involves the use of radiographic methods. However, an imaging-based diagnosis may fail to differentiate lung cancer from non-cancerous lung disease. In this study, we examined several serum proteins in the sera of 198 lung cancer and non-cancerous lung disease patients by multiple-reaction monitoring. We then used a combination of variables to generate a meta-marker model that is useful as a differential diagnostic biomarker.

Large-scale isotype-specific quantification of Serum amyloid A 1/2 by multiple reaction monitoring in crude sera.

Quantification is an essential step in biomarker development. Multiple reaction monitoring (MRM) is a new modified mass spectrometry-based quantification technology that does not require antibody development. Serum amyloid A (SAA) is a positive acute-phase protein identified as a lung cancer biomarker in our previous study. Acute SAA exists in two isoforms with highly similar (92%) amino acid sequences. Until now, studies of SAA have been unable to distinguish between SAA1 and SAA2. To overcome the unavailability of a SAA2-specific antibody, we developed MRM methodology for the verification of SAA1 and SAA2 in clinical crude serum samples from 99 healthy controls and 100 lung adenocarcinoma patients. Differential measurement of SAA1 and SAA2 was made possible for the first time with the developed isotype-specific MRM method. Most healthy control samples had small or no MS/MS peaks of the targeted peptides otherwise, higher peak areas with 10- to 34-fold increase over controls were detected in lung cancer samples. In addition, our SAA1 MRM data demonstrated good agreement with the SAA1 enzyme-linked immunosorbent assay (ELISA) data. Finally, successful quantification of SAA2 in crude serum by MRM, for the first time, shows that SAA2 can be a good biomarker for the detection of lung cancers.

The Haptoglobin ß chain as a supportive biomarker for human lung cancers.

Haptoglobin (Hp) is produced as an acute phase reactant during inflammation, infection, malignant diseases, and several cancers. In proteomics analysis using human blood samples, the Hp peptide levels were about 3-fold higher in lung cancer patients versus normal individuals. This study is aimed at analyzing the elevation of which chain of Hp is closely related to lung cancers and can be a serum biomarker for lung cancers. In Western blot (WB) analysis, we found that the Hp ß chain can be a better diagnostic biomarker for lung cancers. In the result of the Hp ß chain ELISA developed by us, the concentrations of the Hp ß chain in the sera increased about 4-fold in 190 lung adenocarcinoma patients versus 190 healthy controls (8.0 ± 3.8 µg ml(-1)vs. 1.9 ± 1.2 µg ml(-1)). ELISA data showed that the serum levels of the Hp ß chain in breast cancer (1.5 ± 0.5 µg ml(-1)) and hepatocellular carcinoma (HCC) (1.4 ± 1.0 µg ml(-1)) patients remained similar to those of healthy controls. Compared to lung adenocarcinoma, the Hp ß chain levels in the plasma of patients with other respiratory diseases such as tuberculosis (TBC), idiopathic pulmonary fibrosis (IPF) and bronchial asthma (BA) were closer to those of healthy controls. Our data suggest that an increase of the Hp ß chain can be a potential serum biomarker for lung cancers.

Fucosylated glycoproteomic approach to identify a complement component 9 associated with squamous cell lung cancer (SQLC).

Human lung cancer is a major cause of cancer mortality worldwide. Understanding the pathophysiological features and the development of novel biomarkers for diagnosis as well as treatment are major tasks. In the present study, sera from ten SQLC patients and healthy control (HEC) were collected and pooled, respectively. The pooled sera were depleted via an immunoaffinity method and further subjected to fucosylation enrichment. Enriched fucosylated glycoproteins were resolved by SDS-PAGE and subsequently analyzed by LC-ESI-MS/MS. From comparative proteomic analysis, we selected the C9 protein. C9 protein levels were validated by Western blot, protein arrays and the fucosylation levels of C9 by hybrid lectin ELISA (HLE) in the sera of 120 HEC and 118 SQLC patients. The C9 protein level was 6.4-fold higher in SQLC patients compared to HEC, as determined by Western blot analysis. The results were concurrently confirmed by a protein array that showed a C9 level significantly higher in SQLC patients, as compared to HEC, with a sensitivity of 53% and a specificity of 89%. C9 fucosylation levels were significantly higher in SQLC patients compared to HEC (p<0.05) when tested by HLE. These findings suggest that C9 and fucosylated form could serve as a useful marker for SQLC.

Biomarkers for the lung cancer diagnosis and their advances in proteomics.

Over a last decade, intense interest has been focused on biomarker discovery and their clinical uses. This interest is accelerated by the completion of human genome project and the progress of techniques in proteomics. Especially, cancer biomarker discovery is eminent in this field due to its anticipated critical role in early diagnosis, therapy guidance, and prognosis monitoring of cancers. Among cancers, lung cancer, one of the top three major cancers, is the one showing the highest mortality because of failure in early diagnosis. Numerous potential DNA biomarkers such as hypermethylations of the promoters and mutations in K-ras, p53, and protein biomarkers; carcinoembryonic antigen (CEA), CYFRA21-1, plasma kallikrein B1 (KLKB1), Neuron-specific enolase, etc. have been discovered as lung cancer biomarkers. Despite extensive studies thus far, few are turned out to be useful in clinic. Even those used in clinic do not show enough sensitivity, specificity and reproducibility for general use. This review describes what the cancer biomarkers are for, various types of lung cancer biomarkers discovered at present and predicted future advance in lung cancer biomarker discovery with proteomics technology.

The expression patterns of RGS transcripts in platelets.

Regulators of G protein signalling (RGS) are involved in the negative regulation of cell activation processes and are involved in the pathophysiology of cardiovascular diseases. To get some further evidence for a role of RGS proteins in platelets, we determined the expression profile of RGS-specific mRNA in rat platelets using reverse transcription-polymerase chain reaction (RT-PCR) with a poly dT18 primer and transcript-specific primers. We found that RGS2, RGS3, RGS5, RGS6, RGS10, RGS14, RGS16 and RGS18, Leukemia-associated Rho-GEF factor (LARG), and Galpha interacting protein (GAIP) were differentially expressed in platelets. The highest expression rate was found for RGS18 (about 1.3 fold when compared to GAPDH), followed by LARG, RGS6, RGS10 and RGS16 (0.7 to 0.95), whereas expression rates for RGS2, RGS3, RGS5, RGS14, and GAIP were in a range of 0.1 to 0.3. Our results suggest that G-protein-coupled receptor-mediated signalling in platelet may be regulated mainly by RGS 18, 16, 10, 6, and LARG.